Running a wood furnace without the door flapper

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Bufford

Member
Jan 30, 2018
5
Northwestern Ontario
Last night the door flapper on my 1970's vintage Olson wood furnace came off due to a broken hinge. I am hoping that I can get the neighbor with his welder to weld it together in a couple of days. What I am asking; Is it safe to run a wood furnace without the door flapper? I noticed that the smoke backs out through the door when I stoke it. If I open the door slowly I can avoid getting the smoke. Its a cold climate here in Northwestern Ontario and temperatures are going back down in the -30s Celsius at night again for the next few days. I don't want to run the oil furnace at these temps, as it cannot provide the comfort level the wood can.
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio

maple1

Minister of Fire
Sep 15, 2011
10,932
Nova Scotia
Are you talking about a damper door flapper? (Draft flapper?). Or a flapper/sheet hanging inside at the front of the wood chamber that's there to try to stop smoke roll out?
 

laynes69

Minister of Fire
Oct 2, 2006
2,669
Ashland OH
Ding....ding....ding! That was the sound from the old tsc hotblast in the A.M with a cold house! Damn thing burned me everytime it was loaded and it would ding when hit. Don't miss those days! A 6.5 cu.ft firebox loaded with locust hoping to get 7 hours....not again!
 

brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio

laynes69

Minister of Fire
Oct 2, 2006
2,669
Ashland OH
Yeah! I would load large rounds of the hardest wood I had hoping to have a warm house in the morning. Mind you, it was before alot of the improvements, however it would hit 80 then drop in the 60's overnight. There was a forced draft on the unit and I would try to load the furnace around 10 P.M with the luck of 4A.M not having a cold furnace or house. We would wake to the buzz of the forced draft and a cold home. If I still had the furnace it would be 90 in here lol. Nevermind the thought of removing a 5 gallon bucket of creosote every other week to month!
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
Yeah! I would load large rounds of the hardest wood I had hoping to have a warm house in the morning. Mind you, it was before alot of the improvements, however it would hit 80 then drop in the 60's overnight. There was a forced draft on the unit and I would try to load the furnace around 10 P.M with the luck of 4A.M not having a cold furnace or house. We would wake to the buzz of the forced draft and a cold home. If I still had the furnace it would be 90 in here lol. Nevermind the thought of removing a 5 gallon bucket of creosote every other week to month!
My how things have changed, huh?!
 
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Bufford

Member
Jan 30, 2018
5
Northwestern Ontario
It ran fine without the door flapper, I just used a bit of care opening the door for refueling. As Laynes stated I've been burned many times over the years by the lousy thing, but I will put it back. I have had this unit for close to four decades now, and learned a few things about how to get a long burn out of it, because it can be a big fuel hog.

I keep a good deal of ashes covering the grates except for a small hole between the first and center grate to allow a small supply of air under the fire. Most of the air comes over the top of the fire through the vent in the door. I use very dry wood and avoid over fueling. Standing the logs on end particularly large ones work well for a longer burn time.

Since its a two story house the unit is in the basement tied into the ductwork, and the chimney is very long. I do monthly cleanings from behind the unit in the basement, and the creosote is very powdery, which is what it should be. I avoid using unseasoned wood, it just plugs everything up in no time. If the wood is wet I run the oil furnace.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
Standing the logs on end particularly large ones work well for a longer burn time.
Interesting...I was just thinking of trying this recently...because, well, just because...
 

coaly

Fisher Moderator
Staff member
Dec 22, 2007
4,531
NE PA
A door flapper lowers the top of door opening to prevent smoke roll in when opening door. When the outlet is not high enough above door opening, lowering the door opening is one option. When you open the door, draft increases up chimney. The time between opening door and raising flap allows the increased rising gases to evacuate smoke.